The conventional electron beam irradiation methods and apparatuses of this kind have been generally configured to irradiate the objects with high-energy electron beams by utilizing the penetration power. The conventional electron beam irradiation methods and apparatuses of high energy type had a problem that the facilities tended to be large and the energy efficiency was low. To simplify the facilities and improve the energy efficiency, there have been proposed methods and apparatuses for emitting electron beams of low energy type, which enable an object to be irradiated with electron beams as uniformly as possible by using low-energy electron beams, by deflecting electrons, by utilizing a magnetic field, or by reflecting electrons with a reflector plate.
As a typical example of the above idea, technologies are disclosed in Patent Documents 1 and 2 as follows.
The technology in Patent Document 1 discloses an electron beam irradiation apparatus which includes an electron beam irradiation means for emitting electron beams towards an electron beam irradiation area and a plurality of magnetic field deflectors, arranged around the electron beam irradiation area, and configured to generate a plurality of magnetic fields, and also includes a transport means for transporting a three-dimensional object to the electron beam irradiation area.
The technology in Patent Document 2 discloses an electron beam irradiation apparatus which includes an electron beam irradiation means for irradiating a three-dimensional object with electron beams and also includes magnetic field deflectors arranged at a lower position of the object, and a transport means for transporting the object.
According to structures disclosed in Patent Document 1 and 2, by transporting an object on the transport means into the electron beam irradiation area, by generating electron beams by the electron beam irradiation means and emitting electrons to the electron beam irradiation area, and by deflecting emitted electron beams by the respective magnetic field deflectors, electron beams can be directed to various portions of the object.
Meanwhile, these days, plastic containers are widely used which have mouths through which beverage, food, medicine or cosmetic product is filled. The insides of those open-mouthed containers are sterilized to a bacteria-free condition, and those containers are filled with contents and tightly sealed. It has been proposed for a sterilization process to sterilize the interior and exterior surfaces of open-mouthed containers transported at high speed, by using electron beams in place of pharmaceutical agents, the use of which requires large-scale facilities.
An electron beam irradiation apparatus has been proposed, in which, for example, an open-mouthed plastic container, such as a PET bottle, is transferred by the transport means with its center axis at right angles with the transport direction, in other words, with the container laid on its side, to the electron beam irradiation area so as to be irradiated by the electron beam generating means, and the container is further transferred by another transport means, whose bottom is inclined, in such a way that, the rotating open-mouthed container while being rotated, is passed through a space for irradiation by the electron beam generating means, so that both interior and exterior surfaces of the open-mouthed container are irradiated with electron beams to be sterilized efficiently (Refer to Patent Document 3).
To cite another example, an electron beam irradiation apparatus has been proposed, in which an electron beam generating means is arranged to extend longitudinally, a sterilization process room is formed by a radiopaque material in a required length range, including an electron beam irradiation window, and its vicinity, of the electron beam generating means, and the open-mouthed container as an object is transported in upright position by the container transport means from the entrance to the exit of the sterilization process room, and the open-mouthed container is rotated on its axis by a rotating means from a position just before the container reaches the electron beam irradiation window of the electron beam generating means until it has passed the irradiation window to thereby obtain effects of the sterilization process and reduce the size of the apparatus (Refer Patent Document 4).
Furthermore, there has been proposed an example of a method and an apparatus of sterilization capable of sterilizing a number of containers by a single electron beam irradiation means and therefore reducing the size of the whole apparatus, wherein to sterilize the inside of a container by irradiation with electron beams, a container is transported in upright position into the sterilization process room by the transport means, low-energy electron beams from the electron beam irradiation apparatus are deflected to scan the container by an AC magnetic field in the transport direction, and by irradiating the inside of containers one container after another with subdivided electron beams from radial nozzles, to thereby sterilize the inside of a plurality of containers by a single electron beam irradiation means (Refer to Patent Document 5).
Patent Document 1: JP2002-308229A
Patent Document 2: JP11-281798A
Patent Document 3: JP10-268100A
Patent Document 4: JP11-1212A
Patent Document 5: JP2002-104334A